Certain water heaters operate such that water with the water heater's tank is maintained at a set temperature. Generally, a user can select the set temperature using a dial or other input on the water heater. Heat pump water heaters are gaining broader acceptance as a more economic and ecologically-friendly alternative to electric water heaters. Heat pump water heaters include a sealed system for heating water to the set temperature. Certain heat pump water heaters also include a supplemental heating element for heating water. Sealed systems generally heat water less quickly than the supplemental heating elements. However, supplemental heating elements generally heat water less efficiently than the sealed systems.
The sealed systems and the supplemental heating elements are operated in a variety of manners depending upon the current heating mode of the associated water heater appliance. For example, during a vacation mode, neither the sealed system nor the supplemental heating elements are operated. Vacation modes can correspond to when water within the water heater appliance is at the set temperature and/or when the water heater appliance is deactivated by a user. As another example, during an electric heating mode, only the supplemental heating elements are activated and the sealed system is deactivated. A user can select the electric heating mode when the user desires water to be heated rapidly by the water heater appliance. During a heat pump mode, only the sealed system is used to heat water within the water heater appliance. As discussed above, the heat pump mode can heat water efficiently but can also heat water more slowly than the electric mode.
During hybrid heating operations, both the sealed system and the supplemental heating element are used to heat water. Hybrid heating operations are generally initiated when a temperature of water within the water heater falls below a threshold temperature, such as after large water draw events. The sealed system and the supplemental heating element are generally operated simultaneously until the temperature of water within the water heater is restored to the set temperature. Hybrid heating operations can assist with rapidly heating water within the water heater after large water draw events. However, operating both the sealed system and the supplemental heating element consumes valuable energy and can negatively affect an efficiency of the water heater.
Accordingly, methods for operating a water heater appliance efficiently would be useful. In particular, methods for operating a heat pump water heater appliance efficiently during hybrid heating operations would be useful.